A symmetrical grating heterodyne interference secondary diffraction measurement device

Abstract

Disclosed is a symmetric-type grating heterodyne interference secondary diffraction measuring device. The device mainly comprises a laser device, a 1 / 4 wave plate, a light splitting system, a photoelectric conversion system, a polarizing light splitter, a reflector, a grating and the like. Double-frequency lasers emitted by the laser device enter the light splitting system after passing the 1 / 4 wave plate to be divided into three branches, one branch enters the reference photoelectric conversion system, the other two branches enter the positive-negative measuring light path polarizing light splitter, reflected light s is irradiated onto the grating by an incident angle set according to corresponding diffraction grades, occurs interference with light p on a polarizing light splitting face after secondary diffraction and enters the measuring light path photoelectric conversion system. When the grating moves, two signals containing displacement information are detected by the measuring light path photoelectric conversion system, and grading level and vertical displacement can be acquired by solving through the two signals. Whether measured light can return along an original path after secondary diffraction or not only depends on the incident angle and has nothing to do with grating displacement, so that the symmetric-type grating heterodyne interference secondary diffraction measuring device can realize horizontal long stroke and vertical displacement measuring.

Description

technical field [0001] The invention relates to a grating measuring device, in particular to a grating heterodyne interference secondary diffraction measuring device adopting a symmetrical optical path structure. Background technique [0002] With the continuous development of micro-nano processing and manufacturing technology, higher and higher requirements are put forward for the motion accuracy of the ultra-precision workpiece table. Therefore, higher and higher requirements are put forward for the accuracy of the closed-loop feedback measuring instrument that provides real-time position information for the workpiece table. Come higher demands. At present, precision displacement sensors mainly include laser interferometer and grating. Although the laser interferometer has the advantages of high measurement resolution, high measurement accuracy, and high signal-to-noise ratio, its sensitivity to environmental influences limits its application in higher-precision applicati...

AI Technical Summary

Problems solved by technology

The device can effectively overcome the defects that the laser interferometer measurement system is greatly affected by the environment, and has great application prospects in ultra-precision motion platforms

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